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Mono CODEC with Speaker Driver
DESCRIPTION
The WM8940 is a low power, high quality mono CODEC
designed for portable applications such as digital still cameras
or camcorders.
The device integrates support for a differential or single ended
mic, and includes drivers for speakers or headphone, and
mono line output. External component requirements are
reduced as no separate microphone or headphone amplifiers
are required.
Advanced Sigma Delta Converters are used along with digital
decimation and interpolation filters to give high quality audio at
sample rates from 8 to 48ks/s. A selectable high pass filter
and four fully-programmable notch filters are available in the
ADC path. An advanced mixed signal ALC function with noise
gate is provided, while readback of PGA gain during ALC
operation is supported. The digital audio interface supports A-
law and
µ-law
companding.
An on-chip PLL is provided to generate the required Master
Clock from an external reference clock. The PLL clock can
also be output if required elsewhere in the system.
The WM8940 operates at supply voltages from 2.5 to 3.6V,
although the digital supplies can operate at voltages down to
1.71V to save power. Different sections of the chip can also be
powered down under software control using the selectable two
or three wire control interface.
WM8940 is supplied in a very small 4x4mm QFN package,
offering high levels of functionality in minimum board area,
with high thermal performance.
WM8940
FEATURES
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Mono CODEC:
Audio sample rates:8, 11.025, 16, 22.05, 24, 32, 44.1, 48kHz
DAC SNR 98dB, THD -84dB (‘A’-weighted @ 8 – 48ks/s)
ADC SNR 94dB, THD -80dB (‘A’-weighted @ 8 – 48ks/s)
On-chip Headphone/Speaker Driver
- 40mW output power into 16Ω
- BTL speaker drive 0.4W into 8Ω
Additional MONO Line output
Multiple analog or ‘Aux’ inputs, plus analog bypass path
Mic Preamps:
Differential or single end Microphone Interface
- Programmable preamp gain
- Pseudo differential inputs with common mode rejection
- Programmable ALC / Noise Gate in ADC path
Low-noise bias supplied for electret microphones
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OTHER FEATURES
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Digital Playback Limiter
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Programmable high pass filter (wind noise reduction)
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4 notch filters (narrowband noise suppression)
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On-chip PLL
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Low power, low voltage
- 2.5V to 3.6V (digital: 1.71V to 3.6V)
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4x4x0.9mm 24 lead QFN package
APPLICATIONS
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Digital still cameras and camcorders
General purpose mono audio CODEC
WOLFSON MICROELECTRONICS plc
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Pre-Production, Rev 3.0, February 2007,
Copyright
©2007
Wolfson Microelectronics plc
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
